Portable, hand-held lighters are used to ignite combustible materials, typically cigarettes and cigars. Such lighters comprise a fuel in a reservoir, a means of exposing the fuel to air and a means of igniting the fuel. One class of lighters, disposable lighters, require particular caution in their use. These lighters are typically constructed of injection molded thermoplastic and contain a fuel, such as butane, that is normally a gas at atmospheric pressure. In these lighters, the fuel is stored under pressure in a liquid state. Its unauthorized discharge into the air and ignition can cause an explosion. Because of potential hazards associated with explosion. Because of potential hazards associated with unauthorized use of disposable lighters, it is likely that the United States Consumer Product Safety Commission will require that they be made child resistant.
Conventional, disposable lighter designs require two actions for their use. First, a valve on a discharge tube leading from the fuel reservoir to the discharge nozzle must be opened. Second, the gaseous fuel exposed to the oxygen in the air after it is released through the discharge nozzle must be ignited, typically by means of a spark. In conventional, disposable lighter designs, both of the actions required for use are accomplished by grasping the body of the lighter in the palm of the hand with the top of the lighter and the thumb oriented upward and by making a downward motion with the tip of the thumb. The downward motion of the tip of the thumb accomplishes opening of the valve on the discharge tube and ignition of the gaseous fuel.
In conventional flint and spark wheel type lighters, the downward motion of the tip of the thumb pushes down one end of a small lever. The other end of the lever is thereby caused to rise, pulling upward on the valve on discharge tube and opening it. The same downward motion of the tip of the thumb rotates a spark wheel. Rotation of the spark wheel causes its circumference to rub against a sparking medium, such as flint, which emits sparks in the direction of the discharging gas stream.
Both the discharge of the gaseous fuel and the emission of sparks can create hazards, alone and in concert. Mixture of the gaseous fuel with air creates a flammable mixture. Emission of the sparks can ignite this flammable mixture or other flammable substances in the vicinity of the lighter. Both occurrences must, therefore, be controlled to ensure the safety of the lighters in the hands of children.
A variety of child-resistant disposable flint and spark wheel lighter designs have been proposed. In general, these designs use locking mechanisms either to prevent children from opening of the valve on the discharge tube leading from the fuel reservoir or to prevent children from generating a spark. Examples of the first type of design include those disclosed in U.S. Pat. Nos. 4,830,603 (Cirami) and 4,832,596 (Morris). Examples of the second type include those disclosed in U.S. Pat. Nos. 4,717,335 (Loveless) and 4,822,276 (Bisbee). To date, a child-resistant disposable lighter design that prevents both operations necessary for lighter ignition has not been disclosed.